1. Field of the Invention
Aspects of the present invention relate to an image forming apparatus and a power control method thereof.
2. Description of the Related Art
In general, an image forming apparatus, which employs an electrophotographic process forms an electrostatic latent image, on an organic photoconductor (OPC), using a laser beam and then forms an image on a print medium by applying toner to the electrostatic latent image. In order to apply the toner to the electrostatic latent image, the OPC is electrified with positive (+) charges. To this end, a high voltage of several hundred volts is typically applied to the OPC.
International Safety Standards, such as those from UL (Underwriters Laboratories), recommend that users should not be exposed to an electric current of more than 2 mA. This recommendation is made considering the safety of users typically having a body electrical resistance of about 2 KΩ, when they are exposed to a high voltage, and applies to an image forming apparatus, such as a laser printer. Users of an image forming apparatus can be exposed to a high voltage if: a cover is opened to draw out a print medium, jammed while the image forming apparatus is performing a printing operation; a developing unit, containing toner and a photoconductive drum, is separated from the body of the image forming apparatus; or a transfer unit is separated from the body. In order to protect users, a mechanical cover switch is provided to protect a user in such circumstances.
Various international standards recommend that such a mechanical cover switch should be employed in an image forming apparatus, in order to prevent the image forming apparatus from exposing a user to a high voltage. However, if the mechanical cover switch is used more than a predetermined number of times, the switch can fail when a contact terminal is worn away or becomes inelastic. In such circumstances, while the cover of the image forming apparatus is opened, a user may be exposed to a high voltage, produced in a high voltage generating part, thereby threatening his/her safety. In addition, the mechanical cover switch has a complicated structure that increases production costs.